Conventional electric water heaters operate by passing current through a submerged metal coil. The metal coil acts as a resistor giving up heat to the surrounding water. Should the water level in the receptacle reach an unacceptably low level, the build-up of heat in the metal coil may cause damage or create a hazard, hence is undersirable.
While the conventional coil heater has gained widespread acceptance, there exists a need for an electric heating element and associated circuitry which is economical to produce, efficient in operation, and relatively safe. This need occurs in both the original equipment market as well as the replacement market, and in both residential and industrial applications.